Publications

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2012
Li, G, Xie SP.  2012.  Origins of tropical-wide SST biases in CMIP multi-model ensembles. Geophysical Research Letters. 39   10.1029/2012gl053777   AbstractWebsite

Long-standing simulation errors limit the utility of climate models. Overlooked are tropical-wide errors, with sea surface temperature (SST) biasing high or low across all the tropical ocean basins. Our analysis based on Coupled Model Intercomparison Project (CMIP) multi-model ensembles shows that such SST biases can be classified into two types: one with a broad meridional structure and of the same sign across all basins that is highly correlated with the tropical mean; and one with large inter-model variability in the cold tongues of the equatorial Pacific and Atlantic. The first type can be traced back to biases in atmospheric simulations of cloud cover, with cloudy models biasing low in tropical-wide SST. The second type originates from the diversity among models in representing the thermocline depth; models with a deep thermocline feature a warm cold tongue on the equator. Implications for inter-model variability in precipitation climatology and SST threshold for convection are discussed. Citation: Li, G., and S.-P. Xie (2012), Origins of tropical-wide SST biases in CMIP multi-model ensembles, Geophys. Res. Lett., 39, L22703, doi: 10.1029/2012GL053777.

Alexander, MA, Seo H, Xie SP, Scott JD.  2012.  ENSO's Impact on the Gap Wind Regions of the Eastern Tropical Pacific Ocean. Journal of Climate. 25:3549-3565.   10.1175/jcli-d-11-00320.1   Abstract

The recently released NCEP Climate Forecast System Reanalysis (CFSR) is used to examine the response to ENSO in the northeast tropical Pacific Ocean (NETP) during 1979-2009. The normally cool Pacific sea surface temperatures (SSTs) associated with wind jets through the gaps in the Central American mountains at Tehuantepec, Papagayo, and Panama are substantially warmer (colder) than the surrounding ocean during El Nino (La Nina) events. Ocean dynamics generate the ENSO-related SST anomalies in the gap wind regions as the surface fluxes damp the SSTs anomalies, while the Ekman heat transport is generally in quadrature with the anomalies. The ENSO-driven warming is associated with large-scale deepening of the thermocline; with the cold thermocline water at greater depths during El Nino in the NETP, it is less likely to be vertically mixed to the surface, particularly in the gap wind regions where the thermocline is normally very close to the surface. The thermocline deepening is enhanced to the south of the Costa Rica Dome in the Papagayo region, which contributes to the local ENSO-driven SST anomalies. The NETP thermocline changes are due to coastal Kelvin waves that initiate westward-propagating Rossby waves, and possibly ocean eddies, rather than by local Ekman pumping. These findings were confirmed with regional ocean model experiments: only integrations that included interannually varying ocean boundary conditions were able to simulate the thermocline deepening and localized warming in the NETP during El Nino events; the simulation with variable surface fluxes, but boundary conditions that repeated the seasonal cycle, did not.

Richter, I, Xie S-P, Wittenberg AT, Masumoto Y.  2012.  Tropical Atlantic biases and their relation to surface wind stress and terrestrial precipitation. Climate Dynamics. 38:985-1001.   10.1007/s00382-011-1038-9   Abstract
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Chowdary, JS, Xie S-P, Tokinaga H, Okumura YM, Kubota H, Johnson N, Zheng X-T.  2012.  Interdecadal Variations in ENSO Teleconnection to the Indo-Western Pacific for 1870-2007. Journal of Climate. 25:1722-1744.   10.1175/jcli-d-11-00070.1   Abstract
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Tokinaga, H, Xie S-P, Timmermann A, McGregor S, Ogata T, Kubota H, Okumura YM.  2012.  Regional Patterns of Tropical Indo-Pacific Climate Change: Evidence of the Walker Circulation Weakening. Journal of Climate. 25:1689-1710.   10.1175/jcli-d-11-00263.1   Abstract
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Sasaki, H, Xie S-P, Taguchi B, Nonaka M, Hosoda S, Masumoto Y.  2012.  Interannual variations of the Hawaiian Lee Countercurrent induced by potential vorticity variability in the subsurface. Journal of Oceanography. 68:93-111.   10.1007/s10872-011-0074-8   Abstract
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Xie, S-P, Kubokawa A, Kobashi F, Mitsudera H.  2012.  New developments in mode-water research: an introduction. Journal of Oceanography. 68:1-3.   10.1007/s10872-011-0090-8   Abstract
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Oshima, K, Tanimoto Y, Xie SP.  2012.  Regional Patterns of Wintertime SLP Change over the North Pacific and Their Uncertainty in CMIP3 Multi-Model Projections. Journal of the Meteorological Society of Japan. 90A:385-396.   10.2151/jmsj.2012-A23   Abstract

Regional patterns of wintertime sea level pressure (SLP) trends over the North Pacific and their uncertainty were investigated based on the phase 3 of the Coupled Model Intercomparison Project (CMIP3) multi-model projections under the Special Report on Emissions Scenarios (SRES) A1B emission scenario for the 21st century (2000-2099). While the 24-model ensemble mean of the 100-yr SLP trend over the North Pacific shows a northward shift of the Aleutian low (AL), regional patterns of the SLP change vary among the models. Projected changes deepen the AL in several models but it shifts northward in some others. The different response of the AL results in a large inter-model spread over the North Pacific, which is largest of the Northern Hemisphere and comparable in magnitude to the ensemble mean in the same region. This large spread means a high degree of uncertainty in the 100-yr SLP trend over the North Pacific.|For the total uncertainty in the SLP trends over the North Pacific, we examined the relative importance of the internal climate variability and model uncertainty due to different treatments of physical processes and computational scheme. To evaluate each of contributions, a single-realization ensemble using a subset of 10 CMIP3 models is compared to a multi-realization ensemble for the same models in the A1B projections. Additionally the control simulations under preindustrial conditions are examined to evaluate the background internal variability in each of the CMIP3 models. Our analysis shows that both the model uncertainty and internal climate variability contribute to the total uncertainty in the 100-yr SLP trends during the 21st century, while the internal climate variability largely explains the total uncertainty in the 50-yr SLP trends during the first half of the 21st century.|The changes in surface heat flux and North Pacific subtropical gyre in association with the different response of the AL affect regional patterns of the sea surface temperature trends among models.

Xu, L, Xie S-P, Liu Q, Kobashi F.  2012.  Response of the North Pacific subtropical countercurrent and its variability to global warming. Journal of Oceanography. 68:127-137.   10.1007/s10872-011-0031-6   Abstract
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Li, JX, Wang GH, Xie SP, Zhang R, Sun ZY.  2012.  A winter warm pool southwest of Hainan Island due to the orographic wind wake. Journal of Geophysical Research-Oceans. 117   10.1029/2012jc008189   Abstract

A winter warm pool off the southwest coast of Hainan Island is uncovered from high resolution satellite measurements and field observations. The warm pool is characterized by warm temperature relative to the surroundings. It forms in October, intensifies from November to next January, and decays in February. Our results show that the wind wake in the northeast winter monsoon due to the orographic blockage by mountains of Hainan Island plays an important role in generating the warm pool by reducing surface latent heat flux. The core temperature of the warm pool is correlated with the El Nino and Southern Oscillation.

Weller, E, Feng M, Hendon H, Ma J, Xie SP, Caputi N.  2012.  Interannual Variations of Wind Regimes off the Subtropical Western Australia Coast during Austral Winter and Spring. Journal of Climate. 25:5587-5599.   10.1175/jcli-d-11-00324.1   Abstract

Off the Western Australia coast, interannual variations of wind regime during the austral winter and spring are significantly correlated with the Indian Ocean dipole (IOD) and the southern annular mode (SAM) variability. Atmospheric general circulation model experiments forced by an idealized IOD sea surface temperature anomaly field suggest that the IOD-generated deep atmospheric convection anomalies trigger a Rossby wave train in the upper troposphere that propagates into the southern extratropics and induces positive geopotential height anomalies over southern Australia, independent of the SAM. The positive geopotential height anomalies extended from the upper troposphere to the surface, south of the Australian continent, resulting in easterly wind anomalies off the Western Australia coast and a reduction of the high-frequency synoptic storm events that deliver the majority of southwest Australia rainfall during austral winter and spring. In the marine environment, the wind anomalies and reduction of storm events may hamper the western rock lobster recruitment process.

Wang, D, Zhuang W, Xie S-P, Hu J, Shu Y, Wu R.  2012.  Coastal upwelling in summer 2000 in the northeastern South China Sea. Journal of Geophysical Research-Oceans. 117   10.1029/2011jc007465   Abstract
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Ma, J, Xie S-P, Kosaka Y.  2012.  Mechanisms for Tropical Tropospheric Circulation Change in Response to Global Warming. Journal of Climate. 25:2979-2994.   10.1175/jcli-d-11-00048.1   Abstract
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2011
Xu, H, Xu M, Xie S-P, Wang Y.  2011.  Deep Atmospheric Response to the Spring Kuroshio over the East China Sea. Journal of Climate. 24:4959-4972.   10.1175/jcli-d-10-05034.1   Abstract
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Kosaka, Y, Xie S-P, Nakamura H.  2011.  Dynamics of Interannual Variability in Summer Precipitation over East Asia. Journal of Climate. 24:5435-5453.   10.1175/2011jcli4099.1   Abstract
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Li, J, Xie S-P, Cook ER, Huang G, D'Arrigo R, Liu F, Ma J, Zheng X-T.  2011.  Interdecadal modulation of El Nino amplitude during the past millennium. Nature Climate Change. 1:114-118.   10.1038/nclimate1086   Abstract
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Small, JR, Xie S-P, Maloney ED, de Szoeke SP, Miyama T.  2011.  Intraseasonal variability in the far-east pacific: investigation of the role of air-sea coupling in a regional coupled model. Climate Dynamics. 36:867-890.   10.1007/s00382-010-0786-2   Abstract
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Wang, G, Xie S-P, Qu T, Huang RX.  2011.  Deep South China Sea circulation. Geophysical Research Letters. 38   10.1029/2010gl046626   Abstract
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Tokinaga, H, Xie S-P.  2011.  Wave- and Anemometer-Based Sea Surface Wind (WASWind) for Climate Change Analysis. Journal of Climate. 24:267-285.   10.1175/2010jcli3789.1   Abstract
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Yu, W, Han W, Maloney ED, Gochis D, Xie S-P.  2011.  Observations of eastward propagation of atmospheric intraseasonal oscillations from the Pacific to the Atlantic. Journal of Geophysical Research-Atmospheres. 116   10.1029/2010jd014336   Abstract
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